Adverse health effects of biphenyl A in early life. (Correspondence).

In their paper "Parent Biphenyl A (BPA) Accumulation in the Human Maternal--Fetal--Placental Unit," Schonfelder et al. (2002) suggested that "long-term follow-up studies are needed to assess the adverse effects of BPA exposure in early life." Two long-term exposure studies (multigenerational reproductive and developmental studies) have recently been published (Ema et al. 2001; Tyl et al. 2002). Neither provides evidence of any effect of BPA at the levels reported by Schonfelder et al. (2002).

In the long-term study by Ema et al. (2001), conducted by the Chemical Compound Safety Research Institute of Japan, Crj:CD (SD) IGS rats were dosed each day with BPA (0, 0.2, 2.0, 20, or 200 [micro]g/kg/day) by stomach tube over two generations. Assessments included parental growth rate, food intake, reproductive performance, sperm production and motility, gross pathology and histopathology, organ weight, litter size, pup survival and growth, and anogenital distance. In addition, Ema et al. measured levels of several hormones related to reproduction, reflex development, and maze performance. Upon analysis of the data for all of these end points for the parental generation and the [F.sub.1] and [F.sub.2] generations, no consistent evidence of a low-dose effect of BPA was found.

In the study by Tyl et al. (2002), conducted by the Research Triangle Institute in the United States, Sprague-Dawley rats were fed a diet containing BPA at levels from 0 to 7,500 ppm, yielding approximate intakes of 0, 1, 20, 300, 5,000, 50,000, and 500,000 [micro]g/kg/day. Exposures were continued until adulthood of the third-generation offspring. The end points evaluated included parental growth rate, food intake, reproductive performance, sperm production and motility, gross pathology and histopathology, organ weights, litter size, pup survival and growth, and anogenital distance. In addition Tyl et al. measured the day of vaginal opening, preputial separation, and in males, the presence or absence of retained nipples. The lowest observed adverse effect level (LOAED in this study was 50,000 [micro]g/kg/day, and the effects observed at the LOAEL were weight loss or reduction in weight gain. No effects were observed at lower doses.

Reassuringly, the results of the two available long-term studies provide no evidence--despite the exceptional power of the studies--of any effect of BPA exposure at levels near or orders of magnitude higher than those reported by Schonfelder et al. (2002).

The author declares he has no conflict of interest.

REFERENCES

Ema M, Fujii S, Furukawa M, Kiguchi M, Ikka T, Harazono A. 2001. Rat two-generation reproductive toxicity study of bisphenol A. Reprod Toxicol 15:505-523.

Schonfelder G, Wittfoht W, Hopp H, Talsness CE, Paul M, Chahoud I. 2002. Parent bisphenol A accumulation in the human maternal-fetal-placental unit. Environ Health Prospect 110:A703-A707.

Tyl RW, Myers CB, Marr MC, Thomas BF, Keimowitz AR, Brine DR, et al. 2002. Three-generation reproductive toxicity study of dietary bisphenol A in CD Sprague-Dawley rats. Toxicol Sci 68:121-146.

John E. Heinze

Environmental Health Research Foundation

Manassas, Virginia

E-mail: [e-mail]